//===- InstCombineAndOrXor.cpp --------------------------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the visitAnd, visitOr, and visitXor functions. // //===----------------------------------------------------------------------===// #include "InstCombine.h" #include "llvm/Intrinsics.h" #include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Transforms/Utils/CmpInstAnalysis.h" #include "llvm/Support/ConstantRange.h" #include "llvm/Support/PatternMatch.h" using namespace llvm; using namespace PatternMatch; /// AddOne - Add one to a ConstantInt. static Constant *AddOne(Constant *C) { return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); } /// SubOne - Subtract one from a ConstantInt. static Constant *SubOne(ConstantInt *C) { return ConstantInt::get(C->getContext(), C->getValue()-1); } /// isFreeToInvert - Return true if the specified value is free to invert (apply /// ~ to). This happens in cases where the ~ can be eliminated. static inline bool isFreeToInvert(Value *V) { // ~(~(X)) -> X. if (BinaryOperator::isNot(V)) return true; // Constants can be considered to be not'ed values. if (isa(V)) return true; // Compares can be inverted if they have a single use. if (CmpInst *CI = dyn_cast(V)) return CI->hasOneUse(); return false; } static inline Value *dyn_castNotVal(Value *V) { // If this is not(not(x)) don't return that this is a not: we want the two // not's to be folded first. if (BinaryOperator::isNot(V)) { Value *Operand = BinaryOperator::getNotArgument(V); if (!isFreeToInvert(Operand)) return Operand; } // Constants can be considered to be not'ed values... if (ConstantInt *C = dyn_cast(V)) return ConstantInt::get(C->getType(), ~C->getValue()); return 0; } /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp /// predicate into a three bit mask. It also returns whether it is an ordered /// predicate by reference. static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) { isOrdered = false; switch (CC) { case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000 case FCmpInst::FCMP_UNO: return 0; // 000 case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001 case FCmpInst::FCMP_UGT: return 1; // 001 case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010 case FCmpInst::FCMP_UEQ: return 2; // 010 case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011 case FCmpInst::FCMP_UGE: return 3; // 011 case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100 case FCmpInst::FCMP_ULT: return 4; // 100 case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101 case FCmpInst::FCMP_UNE: return 5; // 101 case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110 case FCmpInst::FCMP_ULE: return 6; // 110 // True -> 7 default: // Not expecting FCMP_FALSE and FCMP_TRUE; llvm_unreachable("Unexpected FCmp predicate!"); } } /// getNewICmpValue - This is the complement of getICmpCode, which turns an /// opcode and two operands into either a constant true or false, or a brand /// new ICmp instruction. The sign is passed in to determine which kind /// of predicate to use in the new icmp instruction. static Value *getNewICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, InstCombiner::BuilderTy *Builder) { ICmpInst::Predicate NewPred; if (Value *NewConstant = getICmpValue(Sign, Code, LHS, RHS, NewPred)) return NewConstant; return Builder->CreateICmp(NewPred, LHS, RHS); } /// getFCmpValue - This is the complement of getFCmpCode, which turns an /// opcode and two operands into either a FCmp instruction. isordered is passed /// in to determine which kind of predicate to use in the new fcmp instruction. static Value *getFCmpValue(bool isordered, unsigned code, Value *LHS, Value *RHS, InstCombiner::BuilderTy *Builder) { CmpInst::Predicate Pred; switch (code) { default: llvm_unreachable("Illegal FCmp code!"); case 0: Pred = isordered ? FCmpInst::FCMP_ORD : FCmpInst::FCMP_UNO; break; case 1: Pred = isordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; break; case 2: Pred = isordered ? FCmpInst::FCMP_OEQ : FCmpInst::FCMP_UEQ; break; case 3: Pred = isordered ? FCmpInst::FCMP_OGE : FCmpInst::FCMP_UGE; break; case 4: Pred = isordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; break; case 5: Pred = isordered ? FCmpInst::FCMP_ONE : FCmpInst::FCMP_UNE; break; case 6: Pred = isordered ? FCmpInst::FCMP_OLE : FCmpInst::FCMP_ULE; break; case 7: if (!isordered) return ConstantInt::getTrue(LHS->getContext()); Pred = FCmpInst::FCMP_ORD; break; } return Builder->CreateFCmp(Pred, LHS, RHS); } // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is // guaranteed to be a binary operator. Instruction *InstCombiner::OptAndOp(Instruction *Op, ConstantInt *OpRHS, ConstantInt *AndRHS, BinaryOperator &TheAnd) { Value *X = Op->getOperand(0); Constant *Together = 0; if (!Op->isShift()) Together = ConstantExpr::getAnd(AndRHS, OpRHS); switch (Op->getOpcode()) { case Instruction::Xor: if (Op->hasOneUse()) { // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) Value *And = Builder->CreateAnd(X, AndRHS); And->takeName(Op); return BinaryOperator::CreateXor(And, Together); } break; case Instruction::Or: if (Op->hasOneUse()){ if (Together != OpRHS) { // (X | C1) & C2 --> (X | (C1&C2)) & C2 Value *Or = Builder->CreateOr(X, Together); Or->takeName(Op); return BinaryOperator::CreateAnd(Or, AndRHS); } ConstantInt *TogetherCI = dyn_cast(Together); if (TogetherCI && !TogetherCI->isZero()){ // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1 // NOTE: This reduces the number of bits set in the & mask, which // can expose opportunities for store narrowing. Together = ConstantExpr::getXor(AndRHS, Together); Value *And = Builder->CreateAnd(X, Together); And->takeName(Op); return BinaryOperator::CreateOr(And, OpRHS); } } break; case Instruction::Add: if (Op->hasOneUse()) { // Adding a one to a single bit bit-field should be turned into an XOR // of the bit. First thing to check is to see if this AND is with a // single bit constant. const APInt &AndRHSV = cast(AndRHS)->getValue(); // If there is only one bit set. if (AndRHSV.isPowerOf2()) { // Ok, at this point, we know that we are masking the result of the // ADD down to exactly one bit. If the constant we are adding has // no bits set below this bit, then we can eliminate the ADD. const APInt& AddRHS = cast(OpRHS)->getValue(); // Check to see if any bits below the one bit set in AndRHSV are set. if ((AddRHS & (AndRHSV-1)) == 0) { // If not, the only thing that can effect the output of the AND is // the bit specified by AndRHSV. If that bit is set, the effect of // the XOR is to toggle the bit. If it is clear, then the ADD has // no effect. if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop TheAnd.setOperand(0, X); return &TheAnd; } else { // Pull the XOR out of the AND. Value *NewAnd = Builder->CreateAnd(X, AndRHS); NewAnd->takeName(Op); return BinaryOperator::CreateXor(NewAnd, AndRHS); } } } } break; case Instruction::Shl: { // We know that the AND will not produce any of the bits shifted in, so if // the anded constant includes them, clear them now! // uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal)); ConstantInt *CI = ConstantInt::get(AndRHS->getContext(), AndRHS->getValue() & ShlMask); if (CI->getValue() == ShlMask) // Masking out bits that the shift already masks. return ReplaceInstUsesWith(TheAnd, Op); // No need for the and. if (CI != AndRHS) { // Reducing bits set in and. TheAnd.setOperand(1, CI); return &TheAnd; } break; } case Instruction::LShr: { // We know that the AND will not produce any of the bits shifted in, so if // the anded constant includes them, clear them now! This only applies to // unsigned shifts, because a signed shr may bring in set bits! // uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); ConstantInt *CI = ConstantInt::get(Op->getContext(), AndRHS->getValue() & ShrMask); if (CI->getValue() == ShrMask) // Masking out bits that the shift already masks. return ReplaceInstUsesWith(TheAnd, Op); if (CI != AndRHS) { TheAnd.setOperand(1, CI); // Reduce bits set in and cst. return &TheAnd; } break; } case Instruction::AShr: // Signed shr. // See if this is shifting in some sign extension, then masking it out // with an and. if (Op->hasOneUse()) { uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); Constant *C = ConstantInt::get(Op->getContext(), AndRHS->getValue() & ShrMask); if (C == AndRHS) { // Masking out bits shifted in. // (Val ashr C1) & C2 -> (Val lshr C1) & C2 // Make the argument unsigned. Value *ShVal = Op->getOperand(0); ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName()); return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName()); } } break; } return 0; } /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is /// true, otherwise (V < Lo || V >= Hi). In practice, we emit the more efficient /// (V-Lo) (ConstantExpr::getICmp((isSigned ? ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() && "Lo is not <= Hi in range emission code!"); if (Inside) { if (Lo == Hi) // Trivially false. return ConstantInt::getFalse(V->getContext()); // V >= Min && V < Hi --> V < Hi if (cast(Lo)->isMinValue(isSigned)) { ICmpInst::Predicate pred = (isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT); return Builder->CreateICmp(pred, V, Hi); } // Emit V-Lo CreateAdd(V, NegLo, V->getName()+".off"); Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi); return Builder->CreateICmpULT(Add, UpperBound); } if (Lo == Hi) // Trivially true. return ConstantInt::getTrue(V->getContext()); // V < Min || V >= Hi -> V > Hi-1 Hi = SubOne(cast(Hi)); if (cast(Lo)->isMinValue(isSigned)) { ICmpInst::Predicate pred = (isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT); return Builder->CreateICmp(pred, V, Hi); } // Emit V-Lo >u Hi-1-Lo // Note that Hi has already had one subtracted from it, above. ConstantInt *NegLo = cast(ConstantExpr::getNeg(Lo)); Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off"); Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi); return Builder->CreateICmpUGT(Add, LowerBound); } // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with // any number of 0s on either side. The 1s are allowed to wrap from LSB to // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is // not, since all 1s are not contiguous. static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) { const APInt& V = Val->getValue(); uint32_t BitWidth = Val->getType()->getBitWidth(); if (!APIntOps::isShiftedMask(BitWidth, V)) return false; // look for the first zero bit after the run of ones MB = BitWidth - ((V - 1) ^ V).countLeadingZeros(); // look for the first non-zero bit ME = V.getActiveBits(); return true; } /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask, /// where isSub determines whether the operator is a sub. If we can fold one of /// the following xforms: /// /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 /// /// return (A +/- B). /// Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask, bool isSub, Instruction &I) { Instruction *LHSI = dyn_cast(LHS); if (!LHSI || LHSI->getNumOperands() != 2 || !isa(LHSI->getOperand(1))) return 0; ConstantInt *N = cast(LHSI->getOperand(1)); switch (LHSI->getOpcode()) { default: return 0; case Instruction::And: if (ConstantExpr::getAnd(N, Mask) == Mask) { // If the AndRHS is a power of two minus one (0+1+), this is simple. if ((Mask->getValue().countLeadingZeros() + Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()) break; // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+ // part, we don't need any explicit masks to take them out of A. If that // is all N is, ignore it. uint32_t MB = 0, ME = 0; if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive uint32_t BitWidth = cast(RHS->getType())->getBitWidth(); APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1)); if (MaskedValueIsZero(RHS, Mask)) break; } } return 0; case Instruction::Or: case Instruction::Xor: // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0 if ((Mask->getValue().countLeadingZeros() + Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth() && ConstantExpr::getAnd(N, Mask)->isNullValue()) break; return 0; } if (isSub) return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold"); return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold"); } /// enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C) /// One of A and B is considered the mask, the other the value. This is /// described as the "AMask" or "BMask" part of the enum. If the enum /// contains only "Mask", then both A and B can be considered masks. /// If A is the mask, then it was proven, that (A & C) == C. This /// is trivial if C == A, or C == 0. If both A and C are constants, this /// proof is also easy. /// For the following explanations we assume that A is the mask. /// The part "AllOnes" declares, that the comparison is true only /// if (A & B) == A, or all bits of A are set in B. /// Example: (icmp eq (A & 3), 3) -> FoldMskICmp_AMask_AllOnes /// The part "AllZeroes" declares, that the comparison is true only /// if (A & B) == 0, or all bits of A are cleared in B. /// Example: (icmp eq (A & 3), 0) -> FoldMskICmp_Mask_AllZeroes /// The part "Mixed" declares, that (A & B) == C and C might or might not /// contain any number of one bits and zero bits. /// Example: (icmp eq (A & 3), 1) -> FoldMskICmp_AMask_Mixed /// The Part "Not" means, that in above descriptions "==" should be replaced /// by "!=". /// Example: (icmp ne (A & 3), 3) -> FoldMskICmp_AMask_NotAllOnes /// If the mask A contains a single bit, then the following is equivalent: /// (icmp eq (A & B), A) equals (icmp ne (A & B), 0) /// (icmp ne (A & B), A) equals (icmp eq (A & B), 0) enum MaskedICmpType { FoldMskICmp_AMask_AllOnes = 1, FoldMskICmp_AMask_NotAllOnes = 2, FoldMskICmp_BMask_AllOnes = 4, FoldMskICmp_BMask_NotAllOnes = 8, FoldMskICmp_Mask_AllZeroes = 16, FoldMskICmp_Mask_NotAllZeroes = 32, FoldMskICmp_AMask_Mixed = 64, FoldMskICmp_AMask_NotMixed = 128, FoldMskICmp_BMask_Mixed = 256, FoldMskICmp_BMask_NotMixed = 512 }; /// return the set of pattern classes (from MaskedICmpType) /// that (icmp SCC (A & B), C) satisfies static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C, ICmpInst::Predicate SCC) { ConstantInt *ACst = dyn_cast(A); ConstantInt *BCst = dyn_cast(B); ConstantInt *CCst = dyn_cast(C); bool icmp_eq = (SCC == ICmpInst::ICMP_EQ); bool icmp_abit = (ACst != 0 && !ACst->isZero() && ACst->getValue().isPowerOf2()); bool icmp_bbit = (BCst != 0 && !BCst->isZero() && BCst->getValue().isPowerOf2()); unsigned result = 0; if (CCst != 0 && CCst->isZero()) { // if C is zero, then both A and B qualify as mask result |= (icmp_eq ? (FoldMskICmp_Mask_AllZeroes | FoldMskICmp_Mask_AllZeroes | FoldMskICmp_AMask_Mixed | FoldMskICmp_BMask_Mixed) : (FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_AMask_NotMixed | FoldMskICmp_BMask_NotMixed)); if (icmp_abit) result |= (icmp_eq ? (FoldMskICmp_AMask_NotAllOnes | FoldMskICmp_AMask_NotMixed) : (FoldMskICmp_AMask_AllOnes | FoldMskICmp_AMask_Mixed)); if (icmp_bbit) result |= (icmp_eq ? (FoldMskICmp_BMask_NotAllOnes | FoldMskICmp_BMask_NotMixed) : (FoldMskICmp_BMask_AllOnes | FoldMskICmp_BMask_Mixed)); return result; } if (A == C) { result |= (icmp_eq ? (FoldMskICmp_AMask_AllOnes | FoldMskICmp_AMask_Mixed) : (FoldMskICmp_AMask_NotAllOnes | FoldMskICmp_AMask_NotMixed)); if (icmp_abit) result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_AMask_NotMixed) : (FoldMskICmp_Mask_AllZeroes | FoldMskICmp_AMask_Mixed)); } else if (ACst != 0 && CCst != 0 && ConstantExpr::getAnd(ACst, CCst) == CCst) { result |= (icmp_eq ? FoldMskICmp_AMask_Mixed : FoldMskICmp_AMask_NotMixed); } if (B == C) { result |= (icmp_eq ? (FoldMskICmp_BMask_AllOnes | FoldMskICmp_BMask_Mixed) : (FoldMskICmp_BMask_NotAllOnes | FoldMskICmp_BMask_NotMixed)); if (icmp_bbit) result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_BMask_NotMixed) : (FoldMskICmp_Mask_AllZeroes | FoldMskICmp_BMask_Mixed)); } else if (BCst != 0 && CCst != 0 && ConstantExpr::getAnd(BCst, CCst) == CCst) { result |= (icmp_eq ? FoldMskICmp_BMask_Mixed : FoldMskICmp_BMask_NotMixed); } return result; } /// decomposeBitTestICmp - Decompose an icmp into the form ((X & Y) pred Z) /// if possible. The returned predicate is either == or !=. Returns false if /// decomposition fails. static bool decomposeBitTestICmp(const ICmpInst *I, ICmpInst::Predicate &Pred, Value *&X, Value *&Y, Value *&Z) { // X < 0 is equivalent to (X & SignBit) != 0. if (I->getPredicate() == ICmpInst::ICMP_SLT) if (ConstantInt *C = dyn_cast(I->getOperand(1))) if (C->isZero()) { X = I->getOperand(0); Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth())); Pred = ICmpInst::ICMP_NE; Z = C; return true; } // X > -1 is equivalent to (X & SignBit) == 0. if (I->getPredicate() == ICmpInst::ICMP_SGT) if (ConstantInt *C = dyn_cast(I->getOperand(1))) if (C->isAllOnesValue()) { X = I->getOperand(0); Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth())); Pred = ICmpInst::ICMP_EQ; Z = ConstantInt::getNullValue(C->getType()); return true; } return false; } /// foldLogOpOfMaskedICmpsHelper: /// handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) /// return the set of pattern classes (from MaskedICmpType) /// that both LHS and RHS satisfy static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A, Value*& B, Value*& C, Value*& D, Value*& E, ICmpInst *LHS, ICmpInst *RHS, ICmpInst::Predicate &LHSCC, ICmpInst::Predicate &RHSCC) { if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0; // vectors are not (yet?) supported if (LHS->getOperand(0)->getType()->isVectorTy()) return 0; // Here comes the tricky part: // LHS might be of the form L11 & L12 == X, X == L21 & L22, // and L11 & L12 == L21 & L22. The same goes for RHS. // Now we must find those components L** and R**, that are equal, so // that we can extract the parameters A, B, C, D, and E for the canonical // above. Value *L1 = LHS->getOperand(0); Value *L2 = LHS->getOperand(1); Value *L11,*L12,*L21,*L22; // Check whether the icmp can be decomposed into a bit test. if (decomposeBitTestICmp(LHS, LHSCC, L11, L12, L2)) { L21 = L22 = L1 = 0; } else { // Look for ANDs in the LHS icmp. if (match(L1, m_And(m_Value(L11), m_Value(L12)))) { if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) L21 = L22 = 0; } else { if (!match(L2, m_And(m_Value(L11), m_Value(L12)))) return 0; std::swap(L1, L2); L21 = L22 = 0; } } // Bail if LHS was a icmp that can't be decomposed into an equality. if (!ICmpInst::isEquality(LHSCC)) return 0; Value *R1 = RHS->getOperand(0); Value *R2 = RHS->getOperand(1); Value *R11,*R12; bool ok = false; if (decomposeBitTestICmp(RHS, RHSCC, R11, R12, R2)) { if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { A = R12; D = R11; } else { return 0; } E = R2; R1 = 0; ok = true; } else if (match(R1, m_And(m_Value(R11), m_Value(R12)))) { if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; E = R2; ok = true; } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { A = R12; D = R11; E = R2; ok = true; } } // Bail if RHS was a icmp that can't be decomposed into an equality. if (!ICmpInst::isEquality(RHSCC)) return 0; // Look for ANDs in on the right side of the RHS icmp. if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) { if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; E = R1; ok = true; } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { A = R12; D = R11; E = R1; ok = true; } else { return 0; } } if (!ok) return 0; if (L11 == A) { B = L12; C = L2; } else if (L12 == A) { B = L11; C = L2; } else if (L21 == A) { B = L22; C = L1; } else if (L22 == A) { B = L21; C = L1; } unsigned left_type = getTypeOfMaskedICmp(A, B, C, LHSCC); unsigned right_type = getTypeOfMaskedICmp(A, D, E, RHSCC); return left_type & right_type; } /// foldLogOpOfMaskedICmps: /// try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) /// into a single (icmp(A & X) ==/!= Y) static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, ICmpInst::Predicate NEWCC, llvm::InstCombiner::BuilderTy* Builder) { Value *A = 0, *B = 0, *C = 0, *D = 0, *E = 0; ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); unsigned mask = foldLogOpOfMaskedICmpsHelper(A, B, C, D, E, LHS, RHS, LHSCC, RHSCC); if (mask == 0) return 0; assert(ICmpInst::isEquality(LHSCC) && ICmpInst::isEquality(RHSCC) && "foldLogOpOfMaskedICmpsHelper must return an equality predicate."); if (NEWCC == ICmpInst::ICMP_NE) mask >>= 1; // treat "Not"-states as normal states if (mask & FoldMskICmp_Mask_AllZeroes) { // (icmp eq (A & B), 0) & (icmp eq (A & D), 0) // -> (icmp eq (A & (B|D)), 0) Value* newOr = Builder->CreateOr(B, D); Value* newAnd = Builder->CreateAnd(A, newOr); // we can't use C as zero, because we might actually handle // (icmp ne (A & B), B) & (icmp ne (A & D), D) // with B and D, having a single bit set Value* zero = Constant::getNullValue(A->getType()); return Builder->CreateICmp(NEWCC, newAnd, zero); } else if (mask & FoldMskICmp_BMask_AllOnes) { // (icmp eq (A & B), B) & (icmp eq (A & D), D) // -> (icmp eq (A & (B|D)), (B|D)) Value* newOr = Builder->CreateOr(B, D); Value* newAnd = Builder->CreateAnd(A, newOr); return Builder->CreateICmp(NEWCC, newAnd, newOr); } else if (mask & FoldMskICmp_AMask_AllOnes) { // (icmp eq (A & B), A) & (icmp eq (A & D), A) // -> (icmp eq (A & (B&D)), A) Value* newAnd1 = Builder->CreateAnd(B, D); Value* newAnd = Builder->CreateAnd(A, newAnd1); return Builder->CreateICmp(NEWCC, newAnd, A); } else if (mask & FoldMskICmp_BMask_Mixed) { // (icmp eq (A & B), C) & (icmp eq (A & D), E) // We already know that B & C == C && D & E == E. // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of // C and E, which are shared by both the mask B and the mask D, don't // contradict, then we can transform to // -> (icmp eq (A & (B|D)), (C|E)) // Currently, we only handle the case of B, C, D, and E being constant. ConstantInt *BCst = dyn_cast(B); if (BCst == 0) return 0; ConstantInt *DCst = dyn_cast(D); if (DCst == 0) return 0; // we can't simply use C and E, because we might actually handle // (icmp ne (A & B), B) & (icmp eq (A & D), D) // with B and D, having a single bit set ConstantInt *CCst = dyn_cast(C); if (CCst == 0) return 0; if (LHSCC != NEWCC) CCst = dyn_cast( ConstantExpr::getXor(BCst, CCst) ); ConstantInt *ECst = dyn_cast(E); if (ECst == 0) return 0; if (RHSCC != NEWCC) ECst = dyn_cast( ConstantExpr::getXor(DCst, ECst) ); ConstantInt* MCst = dyn_cast( ConstantExpr::getAnd(ConstantExpr::getAnd(BCst, DCst), ConstantExpr::getXor(CCst, ECst)) ); // if there is a conflict we should actually return a false for the // whole construct if (!MCst->isZero()) return 0; Value *newOr1 = Builder->CreateOr(B, D); Value *newOr2 = ConstantExpr::getOr(CCst, ECst); Value *newAnd = Builder->CreateAnd(A, newOr1); return Builder->CreateICmp(NEWCC, newAnd, newOr2); } return 0; } /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible. Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) { ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B) if (PredicatesFoldable(LHSCC, RHSCC)) { if (LHS->getOperand(0) == RHS->getOperand(1) && LHS->getOperand(1) == RHS->getOperand(0)) LHS->swapOperands(); if (LHS->getOperand(0) == RHS->getOperand(0) && LHS->getOperand(1) == RHS->getOperand(1)) { Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); unsigned Code = getICmpCode(LHS) & getICmpCode(RHS); bool isSigned = LHS->isSigned() || RHS->isSigned(); return getNewICmpValue(isSigned, Code, Op0, Op1, Builder); } } // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E) if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_EQ, Builder)) return V; // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0); ConstantInt *LHSCst = dyn_cast(LHS->getOperand(1)); ConstantInt *RHSCst = dyn_cast(RHS->getOperand(1)); if (LHSCst == 0 || RHSCst == 0) return 0; if (LHSCst == RHSCst && LHSCC == RHSCC) { // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C) // where C is a power of 2 if (LHSCC == ICmpInst::ICMP_ULT && LHSCst->getValue().isPowerOf2()) { Value *NewOr = Builder->CreateOr(Val, Val2); return Builder->CreateICmp(LHSCC, NewOr, LHSCst); } // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0) if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) { Value *NewOr = Builder->CreateOr(Val, Val2); return Builder->CreateICmp(LHSCC, NewOr, LHSCst); } } // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2 // where CMAX is the all ones value for the truncated type, // iff the lower bits of C2 and CA are zero. if (LHSCC == RHSCC && ICmpInst::isEquality(LHSCC) && LHS->hasOneUse() && RHS->hasOneUse()) { Value *V; ConstantInt *AndCst, *SmallCst = 0, *BigCst = 0; // (trunc x) == C1 & (and x, CA) == C2 if (match(Val2, m_Trunc(m_Value(V))) && match(Val, m_And(m_Specific(V), m_ConstantInt(AndCst)))) { SmallCst = RHSCst; BigCst = LHSCst; } // (and x, CA) == C2 & (trunc x) == C1 else if (match(Val, m_Trunc(m_Value(V))) && match(Val2, m_And(m_Specific(V), m_ConstantInt(AndCst)))) { SmallCst = LHSCst; BigCst = RHSCst; } if (SmallCst && BigCst) { unsigned BigBitSize = BigCst->getType()->getBitWidth(); unsigned SmallBitSize = SmallCst->getType()->getBitWidth(); // Check that the low bits are zero. APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); if ((Low & AndCst->getValue()) == 0 && (Low & BigCst->getValue()) == 0) { Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue()); APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue(); Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N); return Builder->CreateICmp(LHSCC, NewAnd, NewVal); } } } // From here on, we only handle: // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler. if (Val != Val2) return 0; // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) return 0; // Make a constant range that's the intersection of the two icmp ranges. // If the intersection is empty, we know that the result is false. ConstantRange LHSRange = ConstantRange::makeICmpRegion(LHSCC, LHSCst->getValue()); ConstantRange RHSRange = ConstantRange::makeICmpRegion(RHSCC, RHSCst->getValue()); if (LHSRange.intersectWith(RHSRange).isEmptySet()) return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); // We can't fold (ugt x, C) & (sgt x, C2). if (!PredicatesFoldable(LHSCC, RHSCC)) return 0; // Ensure that the larger constant is on the RHS. bool ShouldSwap; if (CmpInst::isSigned(LHSCC) || (ICmpInst::isEquality(LHSCC) && CmpInst::isSigned(RHSCC))) ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); else ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); if (ShouldSwap) { std::swap(LHS, RHS); std::swap(LHSCst, RHSCst); std::swap(LHSCC, RHSCC); } // At this point, we know we have two icmp instructions // comparing a value against two constants and and'ing the result // together. Because of the above check, we know that we only have // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know // (from the icmp folding check above), that the two constants // are not equal and that the larger constant is on the RHS assert(LHSCst != RHSCst && "Compares not folded above?"); switch (LHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13 return LHS; } case ICmpInst::ICMP_NE: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_ULT: if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13 return Builder->CreateICmpULT(Val, LHSCst); break; // (X != 13 & X u< 15) -> no change case ICmpInst::ICMP_SLT: if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13 return Builder->CreateICmpSLT(Val, LHSCst); break; // (X != 13 & X s< 15) -> no change case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15 return RHS; case ICmpInst::ICMP_NE: if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1 Constant *AddCST = ConstantExpr::getNeg(LHSCst); Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off"); return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1)); } break; // (X != 13 & X != 15) -> no change } break; case ICmpInst::ICMP_ULT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change break; case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13 return LHS; case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change break; } break; case ICmpInst::ICMP_SLT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change break; case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13 return LHS; case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change break; } break; case ICmpInst::ICMP_UGT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15 return RHS; case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change break; case ICmpInst::ICMP_NE: if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14 return Builder->CreateICmp(LHSCC, Val, RHSCst); break; // (X u> 13 & X != 15) -> no change case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) 13 & X s< 15) -> no change break; } break; case ICmpInst::ICMP_SGT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15 return RHS; case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change break; case ICmpInst::ICMP_NE: if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14 return Builder->CreateICmp(LHSCC, Val, RHSCst); break; // (X s> 13 & X != 15) -> no change case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1 return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true); case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change break; } break; } return 0; } /// FoldAndOfFCmps - Optimize (fcmp)&(fcmp). NOTE: Unlike the rest of /// instcombine, this returns a Value which should already be inserted into the /// function. Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { if (LHS->getPredicate() == FCmpInst::FCMP_ORD && RHS->getPredicate() == FCmpInst::FCMP_ORD) { // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y) if (ConstantFP *LHSC = dyn_cast(LHS->getOperand(1))) if (ConstantFP *RHSC = dyn_cast(RHS->getOperand(1))) { // If either of the constants are nans, then the whole thing returns // false. if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) return ConstantInt::getFalse(LHS->getContext()); return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); } // Handle vector zeros. This occurs because the canonical form of // "fcmp ord x,x" is "fcmp ord x, 0". if (isa(LHS->getOperand(1)) && isa(RHS->getOperand(1))) return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); return 0; } Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { // Swap RHS operands to match LHS. Op1CC = FCmpInst::getSwappedPredicate(Op1CC); std::swap(Op1LHS, Op1RHS); } if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y). if (Op0CC == Op1CC) return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE) return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); if (Op0CC == FCmpInst::FCMP_TRUE) return RHS; if (Op1CC == FCmpInst::FCMP_TRUE) return LHS; bool Op0Ordered; bool Op1Ordered; unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); if (Op1Pred == 0) { std::swap(LHS, RHS); std::swap(Op0Pred, Op1Pred); std::swap(Op0Ordered, Op1Ordered); } if (Op0Pred == 0) { // uno && ueq -> uno && (uno || eq) -> ueq // ord && olt -> ord && (ord && lt) -> olt if (Op0Ordered == Op1Ordered) return RHS; // uno && oeq -> uno && (ord && eq) -> false // uno && ord -> false if (!Op0Ordered) return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); // ord && ueq -> ord && (uno || eq) -> oeq return getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS, Builder); } } return 0; } Instruction *InstCombiner::visitAnd(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyAndInst(Op0, Op1, TD)) return ReplaceInstUsesWith(I, V); // (A|B)&(A|C) -> A|(B&C) etc if (Value *V = SimplifyUsingDistributiveLaws(I)) return ReplaceInstUsesWith(I, V); // See if we can simplify any instructions used by the instruction whose sole // purpose is to compute bits we don't care about. if (SimplifyDemandedInstructionBits(I)) return &I; if (ConstantInt *AndRHS = dyn_cast(Op1)) { const APInt &AndRHSMask = AndRHS->getValue(); // Optimize a variety of ((val OP C1) & C2) combinations... if (BinaryOperator *Op0I = dyn_cast(Op0)) { Value *Op0LHS = Op0I->getOperand(0); Value *Op0RHS = Op0I->getOperand(1); switch (Op0I->getOpcode()) { default: break; case Instruction::Xor: case Instruction::Or: { // If the mask is only needed on one incoming arm, push it up. if (!Op0I->hasOneUse()) break; APInt NotAndRHS(~AndRHSMask); if (MaskedValueIsZero(Op0LHS, NotAndRHS)) { // Not masking anything out for the LHS, move to RHS. Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS, Op0RHS->getName()+".masked"); return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS); } if (!isa(Op0RHS) && MaskedValueIsZero(Op0RHS, NotAndRHS)) { // Not masking anything out for the RHS, move to LHS. Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS, Op0LHS->getName()+".masked"); return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS); } break; } case Instruction::Add: // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS. // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I)) return BinaryOperator::CreateAnd(V, AndRHS); if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I)) return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes break; case Instruction::Sub: // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS. // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I)) return BinaryOperator::CreateAnd(V, AndRHS); // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS // has 1's for all bits that the subtraction with A might affect. if (Op0I->hasOneUse() && !match(Op0LHS, m_Zero())) { uint32_t BitWidth = AndRHSMask.getBitWidth(); uint32_t Zeros = AndRHSMask.countLeadingZeros(); APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros); if (MaskedValueIsZero(Op0LHS, Mask)) { Value *NewNeg = Builder->CreateNeg(Op0RHS); return BinaryOperator::CreateAnd(NewNeg, AndRHS); } } break; case Instruction::Shl: case Instruction::LShr: // (1 << x) & 1 --> zext(x == 0) // (1 >> x) & 1 --> zext(x == 0) if (AndRHSMask == 1 && Op0LHS == AndRHS) { Value *NewICmp = Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType())); return new ZExtInst(NewICmp, I.getType()); } break; } if (ConstantInt *Op0CI = dyn_cast(Op0I->getOperand(1))) if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I)) return Res; } // If this is an integer truncation, and if the source is an 'and' with // immediate, transform it. This frequently occurs for bitfield accesses. { Value *X = 0; ConstantInt *YC = 0; if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) { // Change: and (trunc (and X, YC) to T), C2 // into : and (trunc X to T), trunc(YC) & C2 // This will fold the two constants together, which may allow // other simplifications. Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk"); Constant *C3 = ConstantExpr::getTrunc(YC, I.getType()); C3 = ConstantExpr::getAnd(C3, AndRHS); return BinaryOperator::CreateAnd(NewCast, C3); } } // Try to fold constant and into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } // (~A & ~B) == (~(A | B)) - De Morgan's Law if (Value *Op0NotVal = dyn_castNotVal(Op0)) if (Value *Op1NotVal = dyn_castNotVal(Op1)) if (Op0->hasOneUse() && Op1->hasOneUse()) { Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal, I.getName()+".demorgan"); return BinaryOperator::CreateNot(Or); } { Value *A = 0, *B = 0, *C = 0, *D = 0; // (A|B) & ~(A&B) -> A^B if (match(Op0, m_Or(m_Value(A), m_Value(B))) && match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) && ((A == C && B == D) || (A == D && B == C))) return BinaryOperator::CreateXor(A, B); // ~(A&B) & (A|B) -> A^B if (match(Op1, m_Or(m_Value(A), m_Value(B))) && match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) && ((A == C && B == D) || (A == D && B == C))) return BinaryOperator::CreateXor(A, B); // A&(A^B) => A & ~B { Value *tmpOp0 = Op0; Value *tmpOp1 = Op1; if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_Value(B)))) { if (A == Op1 || B == Op1 ) { tmpOp1 = Op0; tmpOp0 = Op1; // Simplify below } } if (tmpOp1->hasOneUse() && match(tmpOp1, m_Xor(m_Value(A), m_Value(B)))) { if (B == tmpOp0) { std::swap(A, B); } // Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if // A is originally -1 (or a vector of -1 and undefs), then we enter // an endless loop. By checking that A is non-constant we ensure that // we will never get to the loop. if (A == tmpOp0 && !isa(A)) // A&(A^B) -> A & ~B return BinaryOperator::CreateAnd(A, Builder->CreateNot(B)); } } // (A&((~A)|B)) -> A&B if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) || match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1))))) return BinaryOperator::CreateAnd(A, Op1); if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) || match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0))))) return BinaryOperator::CreateAnd(A, Op0); } if (ICmpInst *RHS = dyn_cast(Op1)) if (ICmpInst *LHS = dyn_cast(Op0)) if (Value *Res = FoldAndOfICmps(LHS, RHS)) return ReplaceInstUsesWith(I, Res); // If and'ing two fcmp, try combine them into one. if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(I.getOperand(1))) if (Value *Res = FoldAndOfFCmps(LHS, RHS)) return ReplaceInstUsesWith(I, Res); // fold (and (cast A), (cast B)) -> (cast (and A, B)) if (CastInst *Op0C = dyn_cast(Op0)) if (CastInst *Op1C = dyn_cast(Op1)) { Type *SrcTy = Op0C->getOperand(0)->getType(); if (Op0C->getOpcode() == Op1C->getOpcode() && // same cast kind ? SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntOrIntVectorTy()) { Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0); // Only do this if the casts both really cause code to be generated. if (ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) && ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) { Value *NewOp = Builder->CreateAnd(Op0COp, Op1COp, I.getName()); return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); } // If this is and(cast(icmp), cast(icmp)), try to fold this even if the // cast is otherwise not optimizable. This happens for vector sexts. if (ICmpInst *RHS = dyn_cast(Op1COp)) if (ICmpInst *LHS = dyn_cast(Op0COp)) if (Value *Res = FoldAndOfICmps(LHS, RHS)) return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); // If this is and(cast(fcmp), cast(fcmp)), try to fold this even if the // cast is otherwise not optimizable. This happens for vector sexts. if (FCmpInst *RHS = dyn_cast(Op1COp)) if (FCmpInst *LHS = dyn_cast(Op0COp)) if (Value *Res = FoldAndOfFCmps(LHS, RHS)) return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); } } // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts. if (BinaryOperator *SI1 = dyn_cast(Op1)) { if (BinaryOperator *SI0 = dyn_cast(Op0)) if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && SI0->getOperand(1) == SI1->getOperand(1) && (SI0->hasOneUse() || SI1->hasOneUse())) { Value *NewOp = Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0), SI0->getName()); return BinaryOperator::Create(SI1->getOpcode(), NewOp, SI1->getOperand(1)); } } return Changed ? &I : 0; } /// CollectBSwapParts - Analyze the specified subexpression and see if it is /// capable of providing pieces of a bswap. The subexpression provides pieces /// of a bswap if it is proven that each of the non-zero bytes in the output of /// the expression came from the corresponding "byte swapped" byte in some other /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then /// we know that the expression deposits the low byte of %X into the high byte /// of the bswap result and that all other bytes are zero. This expression is /// accepted, the high byte of ByteValues is set to X to indicate a correct /// match. /// /// This function returns true if the match was unsuccessful and false if so. /// On entry to the function the "OverallLeftShift" is a signed integer value /// indicating the number of bytes that the subexpression is later shifted. For /// example, if the expression is later right shifted by 16 bits, the /// OverallLeftShift value would be -2 on entry. This is used to specify which /// byte of ByteValues is actually being set. /// /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding /// byte is masked to zero by a user. For example, in (X & 255), X will be /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits /// this function to working on up to 32-byte (256 bit) values. ByteMask is /// always in the local (OverallLeftShift) coordinate space. /// static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask, SmallVector &ByteValues) { if (Instruction *I = dyn_cast(V)) { // If this is an or instruction, it may be an inner node of the bswap. if (I->getOpcode() == Instruction::Or) { return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, ByteValues) || CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask, ByteValues); } // If this is a logical shift by a constant multiple of 8, recurse with // OverallLeftShift and ByteMask adjusted. if (I->isLogicalShift() && isa(I->getOperand(1))) { unsigned ShAmt = cast(I->getOperand(1))->getLimitedValue(~0U); // Ensure the shift amount is defined and of a byte value. if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size())) return true; unsigned ByteShift = ShAmt >> 3; if (I->getOpcode() == Instruction::Shl) { // X << 2 -> collect(X, +2) OverallLeftShift += ByteShift; ByteMask >>= ByteShift; } else { // X >>u 2 -> collect(X, -2) OverallLeftShift -= ByteShift; ByteMask <<= ByteShift; ByteMask &= (~0U >> (32-ByteValues.size())); } if (OverallLeftShift >= (int)ByteValues.size()) return true; if (OverallLeftShift <= -(int)ByteValues.size()) return true; return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, ByteValues); } // If this is a logical 'and' with a mask that clears bytes, clear the // corresponding bytes in ByteMask. if (I->getOpcode() == Instruction::And && isa(I->getOperand(1))) { // Scan every byte of the and mask, seeing if the byte is either 0 or 255. unsigned NumBytes = ByteValues.size(); APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255); const APInt &AndMask = cast(I->getOperand(1))->getValue(); for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) { // If this byte is masked out by a later operation, we don't care what // the and mask is. if ((ByteMask & (1 << i)) == 0) continue; // If the AndMask is all zeros for this byte, clear the bit. APInt MaskB = AndMask & Byte; if (MaskB == 0) { ByteMask &= ~(1U << i); continue; } // If the AndMask is not all ones for this byte, it's not a bytezap. if (MaskB != Byte) return true; // Otherwise, this byte is kept. } return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, ByteValues); } } // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be // the input value to the bswap. Some observations: 1) if more than one byte // is demanded from this input, then it could not be successfully assembled // into a byteswap. At least one of the two bytes would not be aligned with // their ultimate destination. if (!isPowerOf2_32(ByteMask)) return true; unsigned InputByteNo = CountTrailingZeros_32(ByteMask); // 2) The input and ultimate destinations must line up: if byte 3 of an i32 // is demanded, it needs to go into byte 0 of the result. This means that the // byte needs to be shifted until it lands in the right byte bucket. The // shift amount depends on the position: if the byte is coming from the high // part of the value (e.g. byte 3) then it must be shifted right. If from the // low part, it must be shifted left. unsigned DestByteNo = InputByteNo + OverallLeftShift; if (InputByteNo < ByteValues.size()/2) { if (ByteValues.size()-1-DestByteNo != InputByteNo) return true; } else { if (ByteValues.size()-1-DestByteNo != InputByteNo) return true; } // If the destination byte value is already defined, the values are or'd // together, which isn't a bswap (unless it's an or of the same bits). if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V) return true; ByteValues[DestByteNo] = V; return false; } /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom. /// If so, insert the new bswap intrinsic and return it. Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) { IntegerType *ITy = dyn_cast(I.getType()); if (!ITy || ITy->getBitWidth() % 16 || // ByteMask only allows up to 32-byte values. ITy->getBitWidth() > 32*8) return 0; // Can only bswap pairs of bytes. Can't do vectors. /// ByteValues - For each byte of the result, we keep track of which value /// defines each byte. SmallVector ByteValues; ByteValues.resize(ITy->getBitWidth()/8); // Try to find all the pieces corresponding to the bswap. uint32_t ByteMask = ~0U >> (32-ByteValues.size()); if (CollectBSwapParts(&I, 0, ByteMask, ByteValues)) return 0; // Check to see if all of the bytes come from the same value. Value *V = ByteValues[0]; if (V == 0) return 0; // Didn't find a byte? Must be zero. // Check to make sure that all of the bytes come from the same value. for (unsigned i = 1, e = ByteValues.size(); i != e; ++i) if (ByteValues[i] != V) return 0; Module *M = I.getParent()->getParent()->getParent(); Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, ITy); return CallInst::Create(F, V); } /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then /// we can simplify this expression to "cond ? C : D or B". static Instruction *MatchSelectFromAndOr(Value *A, Value *B, Value *C, Value *D) { // If A is not a select of -1/0, this cannot match. Value *Cond = 0; if (!match(A, m_SExt(m_Value(Cond))) || !Cond->getType()->isIntegerTy(1)) return 0; // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B. if (match(D, m_Not(m_SExt(m_Specific(Cond))))) return SelectInst::Create(Cond, C, B); if (match(D, m_SExt(m_Not(m_Specific(Cond))))) return SelectInst::Create(Cond, C, B); // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D. if (match(B, m_Not(m_SExt(m_Specific(Cond))))) return SelectInst::Create(Cond, C, D); if (match(B, m_SExt(m_Not(m_Specific(Cond))))) return SelectInst::Create(Cond, C, D); return 0; } /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible. Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) { ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate(); // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) if (PredicatesFoldable(LHSCC, RHSCC)) { if (LHS->getOperand(0) == RHS->getOperand(1) && LHS->getOperand(1) == RHS->getOperand(0)) LHS->swapOperands(); if (LHS->getOperand(0) == RHS->getOperand(0) && LHS->getOperand(1) == RHS->getOperand(1)) { Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); unsigned Code = getICmpCode(LHS) | getICmpCode(RHS); bool isSigned = LHS->isSigned() || RHS->isSigned(); return getNewICmpValue(isSigned, Code, Op0, Op1, Builder); } } // handle (roughly): // (icmp ne (A & B), C) | (icmp ne (A & D), E) if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_NE, Builder)) return V; // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0); ConstantInt *LHSCst = dyn_cast(LHS->getOperand(1)); ConstantInt *RHSCst = dyn_cast(RHS->getOperand(1)); if (LHSCst == 0 || RHSCst == 0) return 0; if (LHSCst == RHSCst && LHSCC == RHSCC) { // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0) if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) { Value *NewOr = Builder->CreateOr(Val, Val2); return Builder->CreateICmp(LHSCC, NewOr, LHSCst); } } // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1) // iff C2 + CA == C1. if (LHSCC == ICmpInst::ICMP_ULT && RHSCC == ICmpInst::ICMP_EQ) { ConstantInt *AddCst; if (match(Val, m_Add(m_Specific(Val2), m_ConstantInt(AddCst)))) if (RHSCst->getValue() + AddCst->getValue() == LHSCst->getValue()) return Builder->CreateICmpULE(Val, LHSCst); } // From here on, we only handle: // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler. if (Val != Val2) return 0; // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) return 0; // We can't fold (ugt x, C) | (sgt x, C2). if (!PredicatesFoldable(LHSCC, RHSCC)) return 0; // Ensure that the larger constant is on the RHS. bool ShouldSwap; if (CmpInst::isSigned(LHSCC) || (ICmpInst::isEquality(LHSCC) && CmpInst::isSigned(RHSCC))) ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); else ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); if (ShouldSwap) { std::swap(LHS, RHS); std::swap(LHSCst, RHSCst); std::swap(LHSCC, RHSCC); } // At this point, we know we have two icmp instructions // comparing a value against two constants and or'ing the result // together. Because of the above check, we know that we only have // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the // icmp folding check above), that the two constants are not // equal. assert(LHSCst != RHSCst && "Compares not folded above?"); switch (LHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: if (LHSCst == SubOne(RHSCst)) { // (X == 13 | X == 14) -> X-13 CreateAdd(Val, AddCST, Val->getName()+".off"); AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst); return Builder->CreateICmpULT(Add, AddCST); } break; // (X == 13 | X == 15) -> no change case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change break; case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15 return RHS; } break; case ICmpInst::ICMP_NE: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13 return LHS; case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true return ConstantInt::getTrue(LHS->getContext()); } case ICmpInst::ICMP_ULT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change break; case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2 // If RHSCst is [us]MAXINT, it is always false. Not handling // this can cause overflow. if (RHSCst->isMaxValue(false)) return LHS; return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false); case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change break; case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15 return RHS; case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change break; } break; case ICmpInst::ICMP_SLT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change break; case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2 // If RHSCst is [us]MAXINT, it is always false. Not handling // this can cause overflow. if (RHSCst->isMaxValue(true)) return LHS; return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false); case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change break; case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15 return RHS; case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change break; } break; case ICmpInst::ICMP_UGT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13 return LHS; case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change break; case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true return ConstantInt::getTrue(LHS->getContext()); case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change break; } break; case ICmpInst::ICMP_SGT: switch (RHSCC) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13 return LHS; case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change break; case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true return ConstantInt::getTrue(LHS->getContext()); case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change break; } break; } return 0; } /// FoldOrOfFCmps - Optimize (fcmp)|(fcmp). NOTE: Unlike the rest of /// instcombine, this returns a Value which should already be inserted into the /// function. Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { if (LHS->getPredicate() == FCmpInst::FCMP_UNO && RHS->getPredicate() == FCmpInst::FCMP_UNO && LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) { if (ConstantFP *LHSC = dyn_cast(LHS->getOperand(1))) if (ConstantFP *RHSC = dyn_cast(RHS->getOperand(1))) { // If either of the constants are nans, then the whole thing returns // true. if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) return ConstantInt::getTrue(LHS->getContext()); // Otherwise, no need to compare the two constants, compare the // rest. return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); } // Handle vector zeros. This occurs because the canonical form of // "fcmp uno x,x" is "fcmp uno x, 0". if (isa(LHS->getOperand(1)) && isa(RHS->getOperand(1))) return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); return 0; } Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { // Swap RHS operands to match LHS. Op1CC = FCmpInst::getSwappedPredicate(Op1CC); std::swap(Op1LHS, Op1RHS); } if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y). if (Op0CC == Op1CC) return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE) return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1); if (Op0CC == FCmpInst::FCMP_FALSE) return RHS; if (Op1CC == FCmpInst::FCMP_FALSE) return LHS; bool Op0Ordered; bool Op1Ordered; unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); if (Op0Ordered == Op1Ordered) { // If both are ordered or unordered, return a new fcmp with // or'ed predicates. return getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS, Builder); } } return 0; } /// FoldOrWithConstants - This helper function folds: /// /// ((A | B) & C1) | (B & C2) /// /// into: /// /// (A & C1) | B /// /// when the XOR of the two constants is "all ones" (-1). Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A, Value *B, Value *C) { ConstantInt *CI1 = dyn_cast(C); if (!CI1) return 0; Value *V1 = 0; ConstantInt *CI2 = 0; if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0; APInt Xor = CI1->getValue() ^ CI2->getValue(); if (!Xor.isAllOnesValue()) return 0; if (V1 == A || V1 == B) { Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1); return BinaryOperator::CreateOr(NewOp, V1); } return 0; } Instruction *InstCombiner::visitOr(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyOrInst(Op0, Op1, TD)) return ReplaceInstUsesWith(I, V); // (A&B)|(A&C) -> A&(B|C) etc if (Value *V = SimplifyUsingDistributiveLaws(I)) return ReplaceInstUsesWith(I, V); // See if we can simplify any instructions used by the instruction whose sole // purpose is to compute bits we don't care about. if (SimplifyDemandedInstructionBits(I)) return &I; if (ConstantInt *RHS = dyn_cast(Op1)) { ConstantInt *C1 = 0; Value *X = 0; // (X & C1) | C2 --> (X | C2) & (C1|C2) // iff (C1 & C2) == 0. if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && (RHS->getValue() & C1->getValue()) != 0 && Op0->hasOneUse()) { Value *Or = Builder->CreateOr(X, RHS); Or->takeName(Op0); return BinaryOperator::CreateAnd(Or, ConstantInt::get(I.getContext(), RHS->getValue() | C1->getValue())); } // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && Op0->hasOneUse()) { Value *Or = Builder->CreateOr(X, RHS); Or->takeName(Op0); return BinaryOperator::CreateXor(Or, ConstantInt::get(I.getContext(), C1->getValue() & ~RHS->getValue())); } // Try to fold constant and into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } Value *A = 0, *B = 0; ConstantInt *C1 = 0, *C2 = 0; // (A | B) | C and A | (B | C) -> bswap if possible. // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible. if (match(Op0, m_Or(m_Value(), m_Value())) || match(Op1, m_Or(m_Value(), m_Value())) || (match(Op0, m_LogicalShift(m_Value(), m_Value())) && match(Op1, m_LogicalShift(m_Value(), m_Value())))) { if (Instruction *BSwap = MatchBSwap(I)) return BSwap; } // (X^C)|Y -> (X|Y)^C iff Y&C == 0 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) && MaskedValueIsZero(Op1, C1->getValue())) { Value *NOr = Builder->CreateOr(A, Op1); NOr->takeName(Op0); return BinaryOperator::CreateXor(NOr, C1); } // Y|(X^C) -> (X|Y)^C iff Y&C == 0 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) && MaskedValueIsZero(Op0, C1->getValue())) { Value *NOr = Builder->CreateOr(A, Op0); NOr->takeName(Op0); return BinaryOperator::CreateXor(NOr, C1); } // (A & C)|(B & D) Value *C = 0, *D = 0; if (match(Op0, m_And(m_Value(A), m_Value(C))) && match(Op1, m_And(m_Value(B), m_Value(D)))) { Value *V1 = 0, *V2 = 0; C1 = dyn_cast(C); C2 = dyn_cast(D); if (C1 && C2) { // (A & C1)|(B & C2) // If we have: ((V + N) & C1) | (V & C2) // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 // replace with V+N. if (C1->getValue() == ~C2->getValue()) { if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+ match(A, m_Add(m_Value(V1), m_Value(V2)))) { // Add commutes, try both ways. if (V1 == B && MaskedValueIsZero(V2, C2->getValue())) return ReplaceInstUsesWith(I, A); if (V2 == B && MaskedValueIsZero(V1, C2->getValue())) return ReplaceInstUsesWith(I, A); } // Or commutes, try both ways. if ((C1->getValue() & (C1->getValue()+1)) == 0 && match(B, m_Add(m_Value(V1), m_Value(V2)))) { // Add commutes, try both ways. if (V1 == A && MaskedValueIsZero(V2, C1->getValue())) return ReplaceInstUsesWith(I, B); if (V2 == A && MaskedValueIsZero(V1, C1->getValue())) return ReplaceInstUsesWith(I, B); } } if ((C1->getValue() & C2->getValue()) == 0) { // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2) // iff (C1&C2) == 0 and (N&~C1) == 0 if (match(A, m_Or(m_Value(V1), m_Value(V2))) && ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N) (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V) return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getContext(), C1->getValue()|C2->getValue())); // Or commutes, try both ways. if (match(B, m_Or(m_Value(V1), m_Value(V2))) && ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N) (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V) return BinaryOperator::CreateAnd(B, ConstantInt::get(B->getContext(), C1->getValue()|C2->getValue())); // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2) // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0. ConstantInt *C3 = 0, *C4 = 0; if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) && (C3->getValue() & ~C1->getValue()) == 0 && match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) && (C4->getValue() & ~C2->getValue()) == 0) { V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield"); return BinaryOperator::CreateAnd(V2, ConstantInt::get(B->getContext(), C1->getValue()|C2->getValue())); } } } // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants. // Don't do this for vector select idioms, the code generator doesn't handle // them well yet. if (!I.getType()->isVectorTy()) { if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D)) return Match; if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C)) return Match; if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D)) return Match; if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C)) return Match; } // ((A&~B)|(~A&B)) -> A^B if ((match(C, m_Not(m_Specific(D))) && match(B, m_Not(m_Specific(A))))) return BinaryOperator::CreateXor(A, D); // ((~B&A)|(~A&B)) -> A^B if ((match(A, m_Not(m_Specific(D))) && match(B, m_Not(m_Specific(C))))) return BinaryOperator::CreateXor(C, D); // ((A&~B)|(B&~A)) -> A^B if ((match(C, m_Not(m_Specific(B))) && match(D, m_Not(m_Specific(A))))) return BinaryOperator::CreateXor(A, B); // ((~B&A)|(B&~A)) -> A^B if ((match(A, m_Not(m_Specific(B))) && match(D, m_Not(m_Specific(C))))) return BinaryOperator::CreateXor(C, B); // ((A|B)&1)|(B&-2) -> (A&1) | B if (match(A, m_Or(m_Value(V1), m_Specific(B))) || match(A, m_Or(m_Specific(B), m_Value(V1)))) { Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C); if (Ret) return Ret; } // (B&-2)|((A|B)&1) -> (A&1) | B if (match(B, m_Or(m_Specific(A), m_Value(V1))) || match(B, m_Or(m_Value(V1), m_Specific(A)))) { Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D); if (Ret) return Ret; } } // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts. if (BinaryOperator *SI1 = dyn_cast(Op1)) { if (BinaryOperator *SI0 = dyn_cast(Op0)) if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && SI0->getOperand(1) == SI1->getOperand(1) && (SI0->hasOneUse() || SI1->hasOneUse())) { Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0), SI0->getName()); return BinaryOperator::Create(SI1->getOpcode(), NewOp, SI1->getOperand(1)); } } // (~A | ~B) == (~(A & B)) - De Morgan's Law if (Value *Op0NotVal = dyn_castNotVal(Op0)) if (Value *Op1NotVal = dyn_castNotVal(Op1)) if (Op0->hasOneUse() && Op1->hasOneUse()) { Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal, I.getName()+".demorgan"); return BinaryOperator::CreateNot(And); } // Canonicalize xor to the RHS. if (match(Op0, m_Xor(m_Value(), m_Value()))) std::swap(Op0, Op1); // A | ( A ^ B) -> A | B // A | (~A ^ B) -> A | ~B if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) { if (Op0 == A || Op0 == B) return BinaryOperator::CreateOr(A, B); if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) { Value *Not = Builder->CreateNot(B, B->getName()+".not"); return BinaryOperator::CreateOr(Not, Op0); } if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) { Value *Not = Builder->CreateNot(A, A->getName()+".not"); return BinaryOperator::CreateOr(Not, Op0); } } // A | ~(A | B) -> A | ~B // A | ~(A ^ B) -> A | ~B if (match(Op1, m_Not(m_Value(A)))) if (BinaryOperator *B = dyn_cast(A)) if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) && Op1->hasOneUse() && (B->getOpcode() == Instruction::Or || B->getOpcode() == Instruction::Xor)) { Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) : B->getOperand(0); Value *Not = Builder->CreateNot(NotOp, NotOp->getName()+".not"); return BinaryOperator::CreateOr(Not, Op0); } if (ICmpInst *RHS = dyn_cast(I.getOperand(1))) if (ICmpInst *LHS = dyn_cast(I.getOperand(0))) if (Value *Res = FoldOrOfICmps(LHS, RHS)) return ReplaceInstUsesWith(I, Res); // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y) if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(I.getOperand(1))) if (Value *Res = FoldOrOfFCmps(LHS, RHS)) return ReplaceInstUsesWith(I, Res); // fold (or (cast A), (cast B)) -> (cast (or A, B)) if (CastInst *Op0C = dyn_cast(Op0)) { CastInst *Op1C = dyn_cast(Op1); if (Op1C && Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ? Type *SrcTy = Op0C->getOperand(0)->getType(); if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntOrIntVectorTy()) { Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0); if ((!isa(Op0COp) || !isa(Op1COp)) && // Only do this if the casts both really cause code to be // generated. ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) && ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) { Value *NewOp = Builder->CreateOr(Op0COp, Op1COp, I.getName()); return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); } // If this is or(cast(icmp), cast(icmp)), try to fold this even if the // cast is otherwise not optimizable. This happens for vector sexts. if (ICmpInst *RHS = dyn_cast(Op1COp)) if (ICmpInst *LHS = dyn_cast(Op0COp)) if (Value *Res = FoldOrOfICmps(LHS, RHS)) return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); // If this is or(cast(fcmp), cast(fcmp)), try to fold this even if the // cast is otherwise not optimizable. This happens for vector sexts. if (FCmpInst *RHS = dyn_cast(Op1COp)) if (FCmpInst *LHS = dyn_cast(Op0COp)) if (Value *Res = FoldOrOfFCmps(LHS, RHS)) return CastInst::Create(Op0C->getOpcode(), Res, I.getType()); } } } // or(sext(A), B) -> A ? -1 : B where A is an i1 // or(A, sext(B)) -> B ? -1 : A where B is an i1 if (match(Op0, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1)) return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1); if (match(Op1, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1)) return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0); // Note: If we've gotten to the point of visiting the outer OR, then the // inner one couldn't be simplified. If it was a constant, then it won't // be simplified by a later pass either, so we try swapping the inner/outer // ORs in the hopes that we'll be able to simplify it this way. // (X|C) | V --> (X|V) | C if (Op0->hasOneUse() && !isa(Op1) && match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) { Value *Inner = Builder->CreateOr(A, Op1); Inner->takeName(Op0); return BinaryOperator::CreateOr(Inner, C1); } return Changed ? &I : 0; } Instruction *InstCombiner::visitXor(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyXorInst(Op0, Op1, TD)) return ReplaceInstUsesWith(I, V); // (A&B)^(A&C) -> A&(B^C) etc if (Value *V = SimplifyUsingDistributiveLaws(I)) return ReplaceInstUsesWith(I, V); // See if we can simplify any instructions used by the instruction whose sole // purpose is to compute bits we don't care about. if (SimplifyDemandedInstructionBits(I)) return &I; // Is this a ~ operation? if (Value *NotOp = dyn_castNotVal(&I)) { if (BinaryOperator *Op0I = dyn_cast(NotOp)) { if (Op0I->getOpcode() == Instruction::And || Op0I->getOpcode() == Instruction::Or) { // ~(~X & Y) --> (X | ~Y) - De Morgan's Law // ~(~X | Y) === (X & ~Y) - De Morgan's Law if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands(); if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { Value *NotY = Builder->CreateNot(Op0I->getOperand(1), Op0I->getOperand(1)->getName()+".not"); if (Op0I->getOpcode() == Instruction::And) return BinaryOperator::CreateOr(Op0NotVal, NotY); return BinaryOperator::CreateAnd(Op0NotVal, NotY); } // ~(X & Y) --> (~X | ~Y) - De Morgan's Law // ~(X | Y) === (~X & ~Y) - De Morgan's Law if (isFreeToInvert(Op0I->getOperand(0)) && isFreeToInvert(Op0I->getOperand(1))) { Value *NotX = Builder->CreateNot(Op0I->getOperand(0), "notlhs"); Value *NotY = Builder->CreateNot(Op0I->getOperand(1), "notrhs"); if (Op0I->getOpcode() == Instruction::And) return BinaryOperator::CreateOr(NotX, NotY); return BinaryOperator::CreateAnd(NotX, NotY); } } else if (Op0I->getOpcode() == Instruction::AShr) { // ~(~X >>s Y) --> (X >>s Y) if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1)); } } } if (ConstantInt *RHS = dyn_cast(Op1)) { if (RHS->isOne() && Op0->hasOneUse()) // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B if (CmpInst *CI = dyn_cast(Op0)) return CmpInst::Create(CI->getOpcode(), CI->getInversePredicate(), CI->getOperand(0), CI->getOperand(1)); // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp). if (CastInst *Op0C = dyn_cast(Op0)) { if (CmpInst *CI = dyn_cast(Op0C->getOperand(0))) { if (CI->hasOneUse() && Op0C->hasOneUse()) { Instruction::CastOps Opcode = Op0C->getOpcode(); if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) && (RHS == ConstantExpr::getCast(Opcode, ConstantInt::getTrue(I.getContext()), Op0C->getDestTy()))) { CI->setPredicate(CI->getInversePredicate()); return CastInst::Create(Opcode, CI, Op0C->getType()); } } } } if (BinaryOperator *Op0I = dyn_cast(Op0)) { // ~(c-X) == X-c-1 == X+(-c-1) if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue()) if (Constant *Op0I0C = dyn_cast(Op0I->getOperand(0))) { Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C); Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C, ConstantInt::get(I.getType(), 1)); return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS); } if (ConstantInt *Op0CI = dyn_cast(Op0I->getOperand(1))) { if (Op0I->getOpcode() == Instruction::Add) { // ~(X-c) --> (-c-1)-X if (RHS->isAllOnesValue()) { Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI); return BinaryOperator::CreateSub( ConstantExpr::getSub(NegOp0CI, ConstantInt::get(I.getType(), 1)), Op0I->getOperand(0)); } else if (RHS->getValue().isSignBit()) { // (X + C) ^ signbit -> (X + C + signbit) Constant *C = ConstantInt::get(I.getContext(), RHS->getValue() + Op0CI->getValue()); return BinaryOperator::CreateAdd(Op0I->getOperand(0), C); } } else if (Op0I->getOpcode() == Instruction::Or) { // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) { Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS); // Anything in both C1 and C2 is known to be zero, remove it from // NewRHS. Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS); NewRHS = ConstantExpr::getAnd(NewRHS, ConstantExpr::getNot(CommonBits)); Worklist.Add(Op0I); I.setOperand(0, Op0I->getOperand(0)); I.setOperand(1, NewRHS); return &I; } } } } // Try to fold constant and into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } BinaryOperator *Op1I = dyn_cast(Op1); if (Op1I) { Value *A, *B; if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) { if (A == Op0) { // B^(B|A) == (A|B)^B Op1I->swapOperands(); I.swapOperands(); std::swap(Op0, Op1); } else if (B == Op0) { // B^(A|B) == (A|B)^B I.swapOperands(); // Simplified below. std::swap(Op0, Op1); } } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){ if (A == Op0) { // A^(A&B) -> A^(B&A) Op1I->swapOperands(); std::swap(A, B); } if (B == Op0) { // A^(B&A) -> (B&A)^A I.swapOperands(); // Simplified below. std::swap(Op0, Op1); } } } BinaryOperator *Op0I = dyn_cast(Op0); if (Op0I) { Value *A, *B; if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) { if (A == Op1) // (B|A)^B == (A|B)^B std::swap(A, B); if (B == Op1) // (A|B)^B == A & ~B return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1)); } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){ if (A == Op1) // (A&B)^A -> (B&A)^A std::swap(A, B); if (B == Op1 && // (B&A)^A == ~B & A !isa(Op1)) { // Canonical form is (B&C)^C return BinaryOperator::CreateAnd(Builder->CreateNot(A), Op1); } } } // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts. if (Op0I && Op1I && Op0I->isShift() && Op0I->getOpcode() == Op1I->getOpcode() && Op0I->getOperand(1) == Op1I->getOperand(1) && (Op1I->hasOneUse() || Op1I->hasOneUse())) { Value *NewOp = Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0), Op0I->getName()); return BinaryOperator::Create(Op1I->getOpcode(), NewOp, Op1I->getOperand(1)); } if (Op0I && Op1I) { Value *A, *B, *C, *D; // (A & B)^(A | B) -> A ^ B if (match(Op0I, m_And(m_Value(A), m_Value(B))) && match(Op1I, m_Or(m_Value(C), m_Value(D)))) { if ((A == C && B == D) || (A == D && B == C)) return BinaryOperator::CreateXor(A, B); } // (A | B)^(A & B) -> A ^ B if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && match(Op1I, m_And(m_Value(C), m_Value(D)))) { if ((A == C && B == D) || (A == D && B == C)) return BinaryOperator::CreateXor(A, B); } } // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) if (ICmpInst *RHS = dyn_cast(I.getOperand(1))) if (ICmpInst *LHS = dyn_cast(I.getOperand(0))) if (PredicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) { if (LHS->getOperand(0) == RHS->getOperand(1) && LHS->getOperand(1) == RHS->getOperand(0)) LHS->swapOperands(); if (LHS->getOperand(0) == RHS->getOperand(0) && LHS->getOperand(1) == RHS->getOperand(1)) { Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS); bool isSigned = LHS->isSigned() || RHS->isSigned(); return ReplaceInstUsesWith(I, getNewICmpValue(isSigned, Code, Op0, Op1, Builder)); } } // fold (xor (cast A), (cast B)) -> (cast (xor A, B)) if (CastInst *Op0C = dyn_cast(Op0)) { if (CastInst *Op1C = dyn_cast(Op1)) if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind? Type *SrcTy = Op0C->getOperand(0)->getType(); if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegerTy() && // Only do this if the casts both really cause code to be generated. ShouldOptimizeCast(Op0C->getOpcode(), Op0C->getOperand(0), I.getType()) && ShouldOptimizeCast(Op1C->getOpcode(), Op1C->getOperand(0), I.getType())) { Value *NewOp = Builder->CreateXor(Op0C->getOperand(0), Op1C->getOperand(0), I.getName()); return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); } } } return Changed ? &I : 0; }